Fix demo form eventlisteners

we use turbolinks and thus we need to init on turbolinks:load

app/javascript/demo.js

@@ -1,4 +1,5 @@
 document.addEventListener("turbolinks:load", function () {
+  tinyforms.init(); // init the tinyforms event listeners
   var demoForm = document.getElementById('demo-form');
   if (!demoForm) {
     return;